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The Influence of the Closure of the East Paleo-Tethys Ocean on Southern South China:Evidences from Kinematics and 40Ar/39Ar Geochronology of the Rongxian Ductile Shear Zone in Southeastern Guangxi

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Acta Geologica Sinica(English Edition) 2024年第5期 1125-1140页

作者： HUANG Wenqiang LI Saisai XIN Liangwei FENG Zuohai ZHANG Hongrui GENG Jieli LIU Kun SHI Chunyan Collaborative Innovation Center for Exploration of Nonferrous Metal Deposits and Efficient Utilization of Resources by the Province and Ministry Guilin University of Technology college of Earth Sciences Guilin University of Technology Institute of geology Chinese Academy of Geological Sciences college of Tourism and Landscape Architecture Guilin University of Technology

The Triassic was a crucial period in the tectonic evolution of the South China Block. Research on tectonic deformation during this period provides information on intracontinental orogenic mechanisms in South China. In this study, alongside thermochronological analyses, we examine the macroscopic and microscopic structural features of the Rongxian ductile shear zone, located south of the Darongshan granite in the southeastern part of Guangxi Province, on the southern margin of South China. Sinistral shear is indicated by the characteristics of rotated σ-type feldspar porphyroclasts, stretching lineations defined by elongated quartz grains and the orientations of quartz c-axes. LA-ICP-MS U-Pb dating of zircons from two samples of granitic mylonite and one of granite yielded ages of ca. 256 Ma. Furthermore, two samples of granitic mylonite yield muscovite40Ar/39Ar plateau ages of 249–246 Ma. These results indicate that the Rongxian ductile shear zone resulted from Early Triassic deformation of the late Permian Darongshan granite. This deformation was likely related to the closure of the eastern Paleo-Tethys Ocean and the subsequent collision of the South China and Indochina blocks, during the early stage of the Indosinian orogeny.

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Effects of typical karst tourist town on the Lijiang River water: from heavy metals to N-nitrosamines

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Journal of Earth Science 2024年

作者： Yuanyu Shan Yuru Su Xinli Xing Bingquan Zhu Honghu Zeng Yuan Zhang Junyu Li Xiaoyu Yan Wenwen Chen Benjian Li college of Environmental Science and Engineering， {1. University of Technology School of Environmental Studies， China University of Geosciences State Key Laboratory of Biogeology and Environmental geology， China University of Geosciences college of arts， {1. University of Technology college of arts and communication， China University of Geosciences 430070 China

N-nitrosamines are nitrogenous organic pollutants with high carcinogenicity to human. Heavy metal pollution in aquatic system is currently a major environmental problem. Tourism in typical karst areas may influence the environment through wastewater discharge. However， it remains unclear whether these activities would cause water pollution. To evaluate the impact of tourism activities in typical tourist towns， this study investigated the occurrence and sources of 1. N-nitrosamines， eight heavy metals （HMs）， and dissolved inorganic nitrogen （DIN） in the Lijiang River and its tributaries. Seven N-nitrosamines were detected as the dominant compounds in N-nitroso-N-ethylaniline （NEA， average of 24.8 ng/L） and N-nitroso-l-proline （NPRO， 20.4 ng/L）， while especially low concentrations of HMs （Mn， Cu， As， Ni， Cr， Co， Pb， and Cd） and DIN (NH4+-N， NO2--N， and NO3--N) were observed. The most important influencing factors were seasonal factors， followed by land-use type and mainstem and tributary factors. Principal component analysis revealed that in the city with developed tourism and relatively less heavy industry， aquaculture and agricultural wastewater were identified as the primary sources of N-nitrosamines. Meanwhile， domestic sewage and agricultural wastewater were found to be the main sources of HMs and DIN， respectively. The ecological risk assessments for all pollutants are relatively low （1.. Therefore， N-nitrosamines， HMs， and DIN pollution caused by tourist activities pose a negligible risk to the Lijiang River.

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Platform Evolution in an Oligo-Miocene Back-arc Basin:An Example from the Central Iran Basin

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 185-206页

作者： Masoud SHARIFI-YAZDI Amirhossein ENAYATI Jamal SALEHI AGHDAM Mohammad BAHREHVAR Seyed Mustafa REZAEI Department of geology Faculty of Earth SciencesGeography and AstronomyUniversity of Vienna1090 Vienna.Austria geology and Geophysics Department Tehran Energy Consultants(TEC Co.)TehranIran School of geology College of ScienceUniversity of TehranTehranIran Department of geology Tarbiat Modares UniversityTehranIran

The Qom Formation is the most important hydrocarbon reservoir target in Central *** Qom platform developed in a back-arc basin during the Oligo-Miocene due to the closing of the Tethyan *** formation consists of a variety of carbonate and non-carbonate facies deposited on a platform ranging from supratidal to basin.A combination of tectonic and eustatic events led to some lateral and vertical facies variations in the study *** third-order depositional sequences and related surfaces were identified regarding vertical facies changes in the studied sections of this Oligo-Miocene *** to all results and data,this succession was initially deposited during the Chattian upon a distally steepened ramp of siliciclastic-carbonate composition,including the Bouma ***,from the late Chattian to the Aquitanian,the platform changed into a homoclinal carbonate ramp with a gentle *** respect to tectonic activity,this phase was a calm period during the deposition of the Qom ***,a drowned carbonate platform and a rimmed shelf emerged during the Burdigalian,terminated by the continental deposits of the Upper Red *** all geological characteristics,three main tectono-eustatic evolutionary phases have been recognized in the Qom back-arcbasin.

关键词： carbonate ramp depositional facies submarine fan eustasy basement faults back-arc basin

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Facies development and sedimentology of the Middle Miocene carbonates of the Raghama Formation, northeastern Saudi Arabia

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Acta Geochimica 2024年第1期43卷 87-96页

作者： Mansour H.Al-Hashim Abdelbaset S.El-Sorogy Meshal Wadani Department of geology and Geophysics College of ScienceKing Saud University2455Riyadh 11451Saudi Arabia

Ragahama Formation comprises a siliciclastic continental deposits followed by marine carbonates, representing prograding alluvial fans from adjacent high hinterlands seaward into lagoons and fringing reef environments. The present work aimed to document the facies development and sedimentology of the Raghama carbonates exposed along the eastern coastal plain of the Red Sea, northwestern Saudi Arabia. Four stratigraphic sections were measured and sampled(D1.D4) and thin sections and major and trace element analyses were prepared and applied for petrographic and geochemical approaches. The carbonates were subdivided into three successive fore-reef, reef-core, and back-reef depositional facies. Sandy stromatolitic boundstone, microbial laminites, dolomitic ooidal grainstone, bioclastic coralline algal wackestone, sandy bioclastic wackestone, and coral boundstones were the reported microfacies types. Petrographic analysis reveals that the studied carbonates were affected by dissolution, dolomitization, and aggrading recrystallization, which affects both the original micrite matrix and grains or acts as fracture and veinlet filling leading to widespread vuggy and moldic porosity. No evidence of physical compaction, suggesting rapid lithification and recrystallization during early diagenesis and prior to substantial burial and intensive flushing by meteoric waters. Most of the original microstructure of corals were leached and destructed. This is indicated by the higher depletion in Sr and Ca levels and increase in Mg,Na, Fe, and Mn levels, especially in section D1. in comparison with the worldwide carbonates.

关键词： Raghama Formation Miocene Diagenesis Geochemistry Saudi Arabia

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Structural Analysis for Qazzaz Metamorphic Core Complex,Northwestern Arabian Shield,Saudi Arabia

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Acta Geologica Sinica(English Edition) 2024年第5期98卷 1187-1201页

作者： Mansour H.AL-HASHIM Osama M.K.KASSEM Department of geology and Geophysics College of ScienceKing Saud University11451 RiyadhSaudi Arabia Department of geology National Research CenterCairoEgypt

Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic ***-three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic *** samples included gneisses rocks,monzogranite,and metavolcano-sedimentary rocks for both the Thalbah and Bayda *** the Rf/j and Fry methods,the axial ratios(XZ)range about 2.20 to 7.1. and 1.90 to 9.1.,*** various rock units,the strain measurements show moderate to highly *** of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain(X).The short axes(Z)based to be subvertical foliation related with a subhorizontal *** results demonstrate that contacts generated at semi-brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic *** concluded that nappe generation in orogens results from pure shear deformation.

关键词： Finite strain metamorphic core complex Qazzaz area Saudi Arabia

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Thermal History of Cambrian Burgess Shale-Type Deposits:New Insights from the Early Cambrian Chengjiang and Qingjiang Fossils of South China

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Journal of Earth Science 2024年第4期35卷 1215-1223页

作者： Yuheng Qiao Linhao Cui Guangyuan Xing Dongjing Fu Chao Chang Robert Gaines Xingliang Zhang State Key Laboratory of Continental Dynamics Shaanxi Key laboratory of Early Life and EnvironmentsDepartment of GeologyNorthwest UniversityXi’an710069China Department of geology Pomona CollegeClaremontCA91711USA

Burgess Shale-type deposits provide a wealth of information on the early evolution of *** that are central to understanding the exceptional preservation of these biotas and the paleoenvironments they inhabited may be obscured by the post-depositional alteration due to metamorphism at depth and weathering near the Earth’s *** over 50 Cambrian BST biotas,the Chengjiang and Qingjiang deposits are well known for their richness of soft-bodied taxa,fidelity of preservation,and Early Cambrian *** alteration via weathering has been well-investigated,the thermal maturity of the units bearing the two biotas has not yet been *** we investigate peak metamorphic temperatures of the two deposits using two independent *** gradient analyses demonstrate that the most fossiliferous sections of the Chengjiang were buried at a maximum depth of∼8500 m in the Early Triassic,corresponding to∼300°C,while the type area of the Qingjiang biota was buried at a maximum depth of∼8700 m in the Early Jurassic,corresponding to∼240°*** geothermometer analyses of fossil carbonaceous material demonstrate that peak temperatures varied across localities with different burial *** two productive sections of the Chengjiang biota were thermally altered at a peak temperature of approximately 300°C,and the main locality of the Qingjiang biota experienced a peak temperature of 238±22°*** results from two independent methods are *** BST deposits for which thermal maturity has been documented,the Qingjiang biota is the least thermally mature,and therefore holds promise for enriching our understanding of BST deposits.

关键词： the Chengjiang Biota the Qingjiang Biota burial history Raman geothermometer thermal history Burgess Shale-type Lagerstätte

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Mineralogy and whole-rock geochemistry of the Oligocene Barail Group of rocks of Belt of Schuppen,Northeast India:Implications for tectono-provenance and paleo-weathering

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Acta Geochimica 2024年第5期43卷 904-932页

作者： Manash Pratim Gogoi Yunpeng Dong Pradip Borgohain Devojit Bezbaruah Arvind Pandey Yadav Krishna Gogoi Garima Konwar Gautam Raj Bawri Bubul Bharali Department of Petroleum Technology Dibrugarh UniversityAssam 786004India Department of geology Northwest UniversityXi’an 710069China Department of Applied geology Dibrugarh UniversityAssam 786004India Department of Statistics Central University of RajasthanAjmer 305817India Department of geology Mizoram UniversityAizawlMizoram 796004India Department of geology Pachhunga University CollegeAizawlMizoram 796001India

The petrographic and geochemical attributes of the Oligocene Barail Group of rocks are used to decipher the likely source area(s)or tectonic domains,as this sequence of rocks was deposited in a foreland basin governed by orogenic domain,namely the North-east Arunachal *** river system that gave rise to the Brahmaputra River(Yarlung-Tsangpo),which flowed through several tectonic domains of the Himalayan ranges,primarily from BomiChayu,Gangadese Granitoid,Higher Himalayan Leucogranites,and Namche Barwa into the proto Bengal Basin now a part of Assam Arakan Basin and Naga Schuppen Belt,was the main source of the sandstone formation of the Barail *** purpose of sandstone petrography,which combines modal analysis with XRF(Major Oxides)and HR-ICPMS(Trace&Rare Earth Elements)research,is to identify the type of source rock(s),their weathering pattern,and its paleo-environmental *** sandstones were formed from recycled orogen and include lithic and sublithic arenite variants with advanced texture and chemical *** sediments were felsic(Th/Co:1.38,Cr/Th:9.78,La/Lu:1..58,Th/Sc:0.99,Eu/Eu*:0.66,La/Sc:3.05,La/Co:4.1.),with contributions from intermediate source rocks and low-rank metamorphics deposited in an active continental margin to a continental island arc *** conditions impacted the sediments of Barails,characterised by being warm and semi-humid to humid which resulted in moderate to a high degree of chemical weathering,as shown by weathering indices like CIA(79.1.),PIA(85.47),CIW(86.9),WIP(32.50),ICV(0.71.,and Th/U(6.03),which were further additionally supported by C-Value(1.01.,PF(1.20),Sr/Cu(2.04),and Rb/Sr(0.97).

关键词： Belt of Schuppen Barail Group Sandstone Petrography Geochemistry Provenance Tectonic setting

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Structural Analysis for Qazzaz Metamorphic Core Complex, Northwestern Arabian Shield, Saudi Arabia

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Acta Geologica Sinica(English Edition) 2024年第5期 1187-1201页

作者： Mansour H.AL-HASHIM Osama M.K.KASSEM Department of geology and Geophysics College of Science King Saud University Department of geology National Research Center

Identifying deformational mechanisms and associated structures at various scales, ranging from regional-scale structures to microscopic fabric, is crucial for the assessment of tectonic development. Thirty-three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic minerals. These samples included gneisses rocks, monzogranite, and metavolcano–sedimentary rocks for both the Thalbah and Bayda groups. Using the Rf/j and Fry methods, the axial ratios(XZ) range about 2.20 to 7.1. and 1.90 to 9.1., respectively. For various rock units, the strain measurements show moderate to highly deformation. Most of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain(X). The short axes(Z) based to be subvertical foliation related with a subhorizontal foliation. The results demonstrate that contacts generated at semi-brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic units. It concluded that nappe generation in orogens results from pure shear deformation.

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Provenance and depositional setting of the Late MiocenePleistocene clastic sediments in the eastern Arabian Peninsula and western Iraq using rare earth elements geochemistry

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Acta Geochimica 2024年第2期43卷 399-410页

作者： Salih M.Awadh Zinah S.Al-Ankaz Mohanad R.A.Al-Owaidi John S.Armstrong-Altrin Department of geology College of ScienceUniversity of BaghdadBaghdadIraq Department of geology College of ScienceUniversity of WasitWasit 52011Iraq Department of Applied geology College of ScienceUniversity of BabylonBabylon 51001Iraq Unidad de Procesos Oceanicos y Costeros Instituto de Ciencias del Mar y LimnologíaUniversidad Nacional Autonoma de MexicoCiudad Universitaria04510 Mexico CityCDMXMexico Department of Marine Sciences Bharathidasan UniversityTiruchirapalliTamil Nadu 620024India

The sandstones of the Late miocene–Pliocene Dibdibba Formation in the Najaf–Karbala Plateau and Basra were examined to determine their source rocks and origin. The rare earth elements(REE) and trace elements(Sc, Co, V, and Th) concentrations in these sandstones revealed that they likely derived from a single source. The steep light rare earth elements(LREE) and flat, heavy rare earth element(HREE) patterns, negative Eu anomaly, and high ΣREE contents in sandstones suggest its derivation from a suggests that a passive continental margin environment and originated from felsic source rocks. The average concentration of ΣREE is 93.5 ppm, which is lower than that of the average crustal compositions like Upper Continental Crust and Post Archean Australian Shale. The higher proportion of LREE compared to HREE implies that these sandstones were recycled and derived from a distal source. The Th/Co, Th/Sc, La/Sc, La/Co, Eu/Eu*and(La/Lu)cn elemental ratios indicated that these Late Miocene–Pliocene sandstones were derived from felsic rocks located in the marginal region of the Arabian Shield.

关键词： REE Dibdibba formation Clastic sediments Passive continental margin

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Water and other volatiles on Mars

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National Science Review 2024年第06期11卷 12-14页

作者： Sen Hu Yubing Gao Zhan Zhou Liang Gao Yangting Lin Key Laboratory of the Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of Sciences college of Earth and Planetary Sciences University of Chinese Academy of Sciences

Mars, the intriguing red planet, is one of the planets most similar to the Earth in our solar system. It is widely accepted that Mars could have had a warm and wet climate in its early history supported by numerous lines of evidence, e.g. topography, canyons, outflow channels, presence of phyllosilicates and evaporative salts,sedimentary formation, and many others (e.g.[1.), and thus Mars is believed to once have a potentially habitable environment which could be able to supply fundamental conditions for the evolution of potential lives.

关键词： ISOTOPIC COMPOSITION MARTIAN ATMOSPHERE SUBSURFACE WATER ABUNDANCE TISSINT H2O CO2

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